U.S. patent application number 15/113717 was filed with the patent office on 2017-01-05 for flaky metal pigment and method of manufacturing flaky metal pigment.
This patent application is currently assigned to TOYO ALUMINIUM KABUSHIKI KAISHA. The applicant listed for this patent is TOYO ALUMINIUM KABUSHIKI KAISHA. Invention is credited to Takayuki NAKAO.
Application Number | 20170001242 15/113717 |
Document ID | / |
Family ID | 54195489 |
Filed Date | 2017-01-05 |
United States Patent
Application |
20170001242 |
Kind Code |
A1 |
NAKAO; Takayuki |
January 5, 2017 |
FLAKY METAL PIGMENT AND METHOD OF MANUFACTURING FLAKY METAL
PIGMENT
Abstract
An object of the present invention is to provide a flaky metal
pigment that is reduced in particle size. According to the flaky
metal pigment of the present invention, in the case where the flaky
metal pigment is measured by a flow-type particle image analyzer,
P50 showing a 50% cumulative frequency of a diameter equivalent to
an area circle in a number distribution is less than 0.500
.mu.m.
Inventors: |
NAKAO; Takayuki; (Osaka-shi,
JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
TOYO ALUMINIUM KABUSHIKI KAISHA |
Osaka-shi, Osaka |
|
JP |
|
|
Assignee: |
TOYO ALUMINIUM KABUSHIKI
KAISHA
Osaka-shi, Osaka
JP
|
Family ID: |
54195489 |
Appl. No.: |
15/113717 |
Filed: |
March 24, 2015 |
PCT Filed: |
March 24, 2015 |
PCT NO: |
PCT/JP2015/058909 |
371 Date: |
July 22, 2016 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
B22F 1/0055 20130101;
C09D 201/00 20130101; C09C 1/64 20130101; B22F 9/04 20130101; B22F
2301/052 20130101; C08K 3/08 20130101; B22F 2009/0804 20130101;
C08K 2201/005 20130101; C09C 1/62 20130101; B22F 9/082 20130101;
B22F 2304/10 20130101; C08K 2003/0812 20130101; C09D 7/40 20180101;
C09D 7/70 20180101; C09D 101/18 20130101; B22F 2998/10 20130101;
C09D 7/61 20180101; B22F 2009/043 20130101 |
International
Class: |
B22F 1/00 20060101
B22F001/00; B22F 9/08 20060101 B22F009/08; C09C 1/64 20060101
C09C001/64; C09D 7/12 20060101 C09D007/12; C09D 101/18 20060101
C09D101/18 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 28, 2014 |
JP |
2014-068359 |
Claims
1-8. (canceled)
9. A flaky metal pigment, said flaky metal pigment being made of
aluminum, and in a case where said flaky metal pigment is measured
by a flow-type particle image analyzer, P50 showing a 50%
cumulative frequency of a diameter equivalent to an area circle in
a number distribution being less than 0.500 .mu.m.
10. The flaky metal pigment according to claim 9, wherein in the
case where said flaky metal pigment is measured by the flow-type
particle image analyzer, Pmax showing a maximum particle diameter
of the diameter equivalent to an area circle in the number
distribution is 5.000 .mu.m or less.
11. The flaky metal pigment according to claim 9, wherein P50/t
showing a ratio of an average thickness t of each said flaky metal
pigment to said P50 is 1 or more and 100 or less.
12. A method of manufacturing a flaky metal pigment, said method
comprising the steps of: preparing slurry including a flake made of
metal; and fine-graining said flake by jetting said slurry at high
pressure.
13. The method of manufacturing a flaky metal pigment according to
claim 12, wherein said fine-graining step includes the steps of:
jetting said slurry from a jetting unit into a reaction chamber at
a pressure of 70 MPa or more; and causing said flake included in
said jetted slurry to collide with a hard body disposed within said
reaction chamber.
14. The method of manufacturing a flaky metal pigment according to
claim 12, wherein said fine-graining step includes the steps of:
jetting said slurry from a jetting unit into a reaction chamber at
a pressure of 70 MPa or more; and causing said slurries jetted from
said jetting unit to collide with each other to cause said flakes
included in said slurries to collide with each other.
15. The method of manufacturing a flaky metal pigment according to
claim 12, wherein said flake is made of aluminum obtained by a
vacuum vapor deposition method.
16. A metallic composition including a flaky metal pigment
according to claim 9.
17. A coated product being obtained by applying a metallic
composition according to claim 16.
Description
TECHNICAL FIELD
[0001] The present invention relates to a flaky metal pigment and a
method of manufacturing a flaky metal pigment.
BACKGROUND ART
[0002] Conventionally, since flake-shaped metal pigments (which
will be hereinafter also referred to as "flaky metal pigments")
exhibit an excellent metallic texture when being used to form a
coating film, such pigments have been used for paint, ink, and the
like. Such flaky metal pigments have been conventionally
manufactured by the ball mill method as described below.
[0003] First, metal powder as a raw material, an organic solvent,
and a grinding aid such as a higher fatty acid are first prepared.
Then, these materials are introduced into a cylindrical drum, into
which media (balls) are introduced. Then, the drum is rotated to
apply mechanical force to the metal powder within the drum, thereby
allowing flaking of the metal powder.
[0004] Such a ball mill method is suitable to manufacture powder
having an average particle diameter of 10 .mu.m or more and the
maximum particle diameter of more than 20 .mu.m. Thus, the
manufactured powder is widely utilized in coating techniques such
as spray coating and screen printing.
[0005] In recent years, a coating technique implemented by ink
jetting has been started to be employed in place of the coating
technique as described above. Accordingly, there has been an
increased demand for metallic printing by which a metallic image
and the like are printed using this coating technique. However,
when flaky metal pigments produced by the conventional ball mill
method are used in ink jetting for the purpose of conducting
metallic printing, the following problem occurs.
[0006] In ink jetting, ink is discharged at high speed from an
ink-jet nozzle and the discharged ink is coated on a base body such
as a paper medium to form a coating film. Thus, an image is formed
by arrangement of this coating film. However, a flaky metal pigment
is not small enough for the diameter of the hole of the ink-jet
nozzle used in an industrially-applied or non-commercially-applied
general ink jetting process, which causes blockage in the ink-jet
nozzle, with the result that ink cannot be discharged.
[0007] In order to solve the above-described problems, an attempt
has been made to produce flaky metal pigments reduced in particle
diameter, thereby allowing metallic printing implemented by ink
jetting. For example, Japanese Patent Laying-Open No. 2008-174712
(Cited Document 1) discloses a method of forming an aluminum vapor
deposition layer by the vacuum vapor deposition method, which is
subjected to an ultrasonic treatment in a solvent so as to be
peeled, fine-grained and distributed, thereby producing an aluminum
pigment having a particle size smaller than that in the
conventional case.
CITATION LIST
Patent Document
[0008] PTD 1: Japanese Patent Laying-Open No. 2008-174712
SUMMARY OF INVENTION
Technical Problem
[0009] However, according to recent improvements in ink-jet
printing technique, formation of an image with extremely high
definition has been increasingly required. Forming an image with
high definition requires pigments further reduced in particle size.
The same applies also to metallic printing implemented by ink
jetting. Accordingly, metal pigments further reduced in particle
size need to be provided.
[0010] The present invention has been made in light of the
above-described circumstances. An object of the present invention
is to provide a flaky metal pigment reduced in particle size and a
method of manufacturing a flaky metal pigment, both of which can be
utilized for metallic printing implemented by ink jetting.
Solution to Problem
[0011] In order to solve the above-described problems, the present
inventor has conducted earnest studies for manufacturing a metal
pigment that is fine-grained in particle diameter, which can be
suitably utilized for metallic printing implemented by ink jetting.
The studies showed that the method as disclosed in PTD 1 requires
an extremely long processing time to achieve a fine-grained
aluminum pigment, and also that it is difficult to fine-grain a
metal pigment to a required degree.
[0012] Accordingly, the present inventor considered that pigment
needs to be fine-grained by the technique different from the
conventional techniques. Thus, upon conducting further studies, the
inventor has found that a flake having a surface that is
sufficiently large for its thickness is produced and jetted at
high-pressure, thereby applying external force to this flake, so
that this flake can be remarkably fine-grained. The present
invention has been completed based on this finding.
[0013] Specifically, a flaky metal pigment according to one
embodiment of the present invention is characterized in that, in a
case where the flaky metal pigment is measured by a flow-type
particle image analyzer, P50 showing a 50% cumulative frequency of
a diameter equivalent to an area circle in a number distribution is
less than 0.500 .mu.m.
[0014] In the above-described flaky metal pigment, preferably, in
the case where the flaky metal pigment is measured by the flow-type
particle image analyzer, Pmax showing a maximum particle diameter
of the diameter equivalent to an area circle in the number
distribution is 5.000 .mu.m or less.
[0015] In the above-described flaky metal pigment, preferably,
P50/t showing a ratio of an average thickness t of each flaky metal
pigment to P50 is 1 or more and 100 or less.
[0016] In the above-described flaky metal pigment, preferably, the
flaky metal pigment is made of aluminum.
[0017] A method of manufacturing a flaky metal pigment according to
one embodiment of the present invention includes the steps of:
preparing slurry including a flake made of metal; and fine-graining
the flake by jetting the slurry at high pressure.
[0018] In the above-described method of manufacturing a flaky metal
pigment, preferably, the fine-graining step includes the steps of:
jetting the slurry from a jetting unit into a reaction chamber at a
pressure of 70 MPa or more; and causing the flake included in the
jetted slurry to collide with a hard body disposed within the
reaction chamber.
[0019] In the above-described method of manufacturing a flaky metal
pigment, preferably, the fine-graining step includes the steps of:
jetting the slurry from a jetting unit into a reaction chamber at a
pressure of 70 MPa or more; and causing the slurries jetted from
the jetting units to collide with each other to cause the flakes
included in the slurries to collide with each other. In addition,
it is preferable that two or more jetting units are provided. In
this case, the slurry is jetted from each of the jetting units, and
flakes included in the jetted slurries collide with each other, so
that the flakes each can be fine-grained efficiently.
[0020] In the above-described method of manufacturing a flaky metal
pigment, preferably, the flake is made of aluminum obtained by a
vacuum vapor deposition method.
Advantageous Effects of Invention
[0021] According to the above description, it becomes possible to
provide a flaky metal pigment that is reduced in particle size and
a method of manufacturing a flaky metal pigment, both of which can
be utilized for metallic printing implemented by ink jetting.
BRIEF DESCRIPTION OF DRAWINGS
[0022] FIG. 1 is a flow diagram showing an example of a method of
manufacturing a flaky metal pigment according to an embodiment.
[0023] FIG. 2 is a schematic diagram for illustrating the shape of
a flake included in slurry to be prepared, in accordance with the
method of manufacturing a flaky metal pigment according to the
embodiment.
[0024] FIG. 3 is a flow diagram for illustrating an example of the
fine-graining step.
[0025] FIG. 4 is a schematic diagram for illustrating an example of
the fine-graining step.
[0026] FIG. 5 is a flow diagram for illustrating another example of
the fine-graining step.
[0027] FIG. 6 is a schematic diagram for illustrating another
example of the fine-graining step.
DESCRIPTION OF EMBODIMENTS
[0028] Hereinafter described will be embodiments of a flaky metal
pigment of the present invention, a metallic composition containing
the same and a coated product, and a method of manufacturing the
flaky metal pigment.
First Embodiment: Flaky Metal Pigment
[0029] As to a flaky metal pigment according to the first
embodiment, P50 showing a 50% cumulative frequency of a diameter
equivalent to an area circle in a number distribution measured by a
flow-type particle image analyzer is less than 0.500 .mu.m. The
"diameter equivalent to an area circle" is a diameter of a circle
equivalent to a projected area of a particle image that has been
taken. "P50" represents a particle size at which the cumulative
frequency reaches 50% in the cumulative distribution of the
diameter equivalent to an area circle in the number distribution.
It is to be noted that the "particle size" means the
above-mentioned "diameter equivalent to an area circle" unless
specifically explained in the specification of the present
application.
[0030] The above-described flaky metal pigment is made of metal. It
is preferable that metal exhibits an excellent metallic texture in
image formation, and can be aluminum, copper, iron, stainless
steel, and nickel, for example. Particularly, aluminum is
preferable since it can exhibit an excellent metallic texture and
also in terms of the manufacturing cost. In addition, the term
"metallic texture" used in the present specification means a
texture that shows a color tone with high luminance like a
glittering metallic luster and can be visually recognized.
[0031] The above-described aluminum is as a matter of course made
of metal aluminum, and may be made of an aluminum alloy or a
mixture thereof. An aluminum alloy can be an alloy and the like
made of Al that is main metal and at least one or more types
selected from silicon (Si), magnesium (Mg) and transition metal. It
is preferable that the flaky metal pigment is made of Al since it
can be industrially manufactured at low cost and exhibits a
relatively high metallic texture.
[0032] Furthermore, examples of the flow-type particle image
analyzer can be "FPIA-2100", "FPIA-3000", and "FPIA-3000S" (trade
names) manufactured by Sysmex Corporation. Furthermore, in the
present specification, "P50" measured by the flow-type particle
image analyzer means a value measured on the following measurement
conditions. Furthermore, "Pmax" and "P10", which will be described
later, also mean the values measured on the same measurement
conditions.
[0033] Image pick-up unit: high-magnification image pick-up
unit
[0034] Magnification: 40 times (20-times ocular lens.times.2-times
object lens)
[0035] Measurement mode: HPF measurement mode
[0036] Measurement time: about 2 minutes
[0037] Measurement solvent: ethanol
[0038] Binarized threshold value setting coefficient: 85%
[0039] Dilution ratio by solvent during measurement: 2000 times
[0040] Sheath liquid: ethanol.
[0041] The flaky metal pigment having P50 of less than 0.500 .mu.m
tends to be smaller in particle size and sharper in particle size
distribution than a flaky metal pigment manufactured by the
conventional ball mill method and an aluminum pigment manufactured
by the manufacturing method disclosed in PTD 1. Such a flaky metal
pigment according to the first embodiment can be suitably used for
an application that requires a flaky metal pigment reduced in
particle size, for example, for high-definition ink jetting. In the
case where the flaky metal pigment according to the first
embodiment is used for metallic printing implemented by ink
jetting, the following effects can be achieved.
[0042] Specifically, since the conventional flaky metal pigment has
a relatively large particle size, the total number of metal
pigments in the coating film coated by ink jetting on a base body
(a paper medium and the like) tended to be less than the desired
number. Furthermore, the conventional flaky metal pigment has a
relatively large particle size, which causes a problem that an
ink-jet nozzle for discharging a metallic composition gets clogged
by repeated discharge of the composition.
[0043] In contrast, a flaky metal pigment according to the first
embodiment tends to be smaller in particle size and more uniform in
particle size than the conventional flaky metal pigment.
Accordingly, the total number of metal pigments in the metallic
composition coated by ink jetting on a base body (a paper medium
and the like) can be increased. Therefore, in the case where the
flaky metal pigment according to the first embodiment is used, the
coating film (image) formed on a base body can exhibit high
shielding performance. Also, the number of times of repeated
coating can be reduced, and further, clogging of the ink-jet nozzle
can be suppressed. Furthermore, in the case where the shielding
performance comparable to that of the metallic composition made
using conventional flaky metal pigments only has to be achieved, it
is also expected that the content of the flaky metal pigments in
the metallic composition can be reduced, which leads to reduction
in manufacturing cost.
[0044] In such a flaky metal pigment according to the first
embodiment, Pmax showing the value of the maximum particle diameter
of the diameter equivalent to an area circle in the number
distribution measured by a flow-type particle image analyzer is
preferably 5 .mu.m or less, and more preferably 3 .mu.m or less.
The Pmax having a value of 5 .mu.m or less allows further higher
shielding performance. Also, since the particle size distribution
becomes sharp, clogging of the ink-jet nozzle used for ink jetting
is further suppressed, thereby allowing formation of an image with
high definition.
[0045] Furthermore, in the flaky metal pigment according to the
first embodiment, average thickness t is preferably 5 nm or more
and 25 nm or less, and more preferably 10 nm or more and 25 nm or
less.
[0046] In this case, average thickness t can be measured as
described below. Specifically, several drops of flaky metal
pigments diluted with acetone are dripped onto a glass substrate,
and then, naturally dried and hardened. Then, an atomic force
microscope (trade name: "Nanopics 1000" manufactured by Seiko
Instruments Inc.) is used to extract 20 points of flaky metal
pigments forcibly oriented on the glass substrate and measure each
thickness in a tapping mode. Then, the average value of thicknesses
at remaining 14 points among the thicknesses measured at 20 points
except for thicknesses having higher values at three points and
lower values at three points is calculated. This calculated average
value is defined as an average thickness t.
[0047] When average thickness t is less than 5 nm, most of light
transmits through the flaky metal pigment, which may cause
deterioration in metallic texture, deterioration in shielding
performance, and the like. Furthermore, in the case where flaky
metal pigments of average thickness t of less than 5 nm are used
for the metallic composition for ink jetting, it is necessary to
significantly increase the content of the flaky metal pigments in
the ink composition for sufficiently exhibiting a metallic texture.
This may result in clogging of the ink-jet nozzle.
[0048] On the other hand, when average thickness t exceeds 25 nm,
the particle size distribution of the flaky metal pigments tends to
be broad in the manufacturing process described later, with the
result that the brightness may decrease and the metallic texture
may also deteriorate. Furthermore, in the case where the metallic
composition including such flaky metal pigments is coated on a base
body, irregular reflection of light resulting from overlapping of
the flaky metal pigments on the base body becomes remarkable, and
thus, an excellent metallic texture is less likely to be
achieved.
[0049] Furthermore, it is preferable that the flaky metal pigment
according to the first embodiment has a uniform thickness. This
allows formation of a coating film having a homogeneous metallic
texture. Furthermore, the flaky metal pigment has two surfaces that
face each other so as to extend approximately in its thickness
direction. It is preferable that these surfaces are flat. Also in
this case, a coating film having a more homogeneous metallic
texture can be formed.
[0050] Furthermore, in the flaky metal pigment according to the
first embodiment, P50/t showing a ratio of average thickness t to
P50 (in which case the unit of P50 and the unit oft are the same)
is preferably 1 or more and 100 or less, more preferably 3 or more
and 100 or less, and further more preferably 10 or more and 50 or
less.
[0051] In the case where the aspect ratio expressed by P50/t is
less than 1, the thickness tends to be large relative to the
particle size of the flaky metal pigment. Accordingly, when the
metallic composition containing such pigments is coated on a base
body, irregular refraction of light resulting from overlapping of
the flaky metal pigments on the base body becomes remarkable, so
that an excellent metallic texture is less likely to be
achieved.
[0052] On the other hand, in the case where the aspect ratio
expressed by P50/t exceeds 100, the thickness of the flaky metal
pigment tends to be extremely thin. Accordingly, light transmits
through the flaky metal pigment, which may cause deterioration in
the shielding performance and the like.
[0053] Furthermore, in the flaky metal pigment according to the
first embodiment, Pmax/P10 showing a ratio of P10 to Pmax (in which
case the unit of Pmax and the unit of P10 are the same) is
preferably 1 or more and 18 or less, and more preferably 2 or more
and 15 or less, wherein P10 is a value of the 10% cumulative
frequency in the number distribution of the flaky metal pigments
measured by the flow-type particle image analyzer.
[0054] In the case where Pmax/P10 is 1 or more and 18 or less, the
particle size distribution of the flaky metal pigments is sharp.
Accordingly, in the case where such flaky metal pigments are used
for a metallic composition for ink jetting, clogging of the ink-jet
nozzle is further suppressed while an image with high definition
can be formed. Furthermore, the formed image can exhibit an
excellent metallic texture.
Second Embodiment: Metallic Composition
[0055] The metallic composition according to the second embodiment
is a metallic composition including a flaky metal pigment according
to the above-described first embodiment.
[0056] The usage of the metallic composition according to the
second embodiment is not particularly limited, but for example, can
be used for paint, ink, a resin molded product, cosmetic materials,
wiring of an electronic circuit component, and the like for which a
metallic texture and a high degree of definition are required. The
metallic composition according to the second embodiment includes a
flaky metal pigment that tends to be smaller in particle size than
the conventional pigment. Accordingly, for example, in the case
where the metallic composition according to the second embodiment
is used as ink for ink jetting, an excellent metallic texture can
be achieved while a coating film (image) having excellent shielding
performance can be formed even if the discharge amount or the
number of times of repeated coating is less than that in the
conventional case. Furthermore, the metallic composition according
to the second embodiment can suppress clogging of the ink-jet
nozzle.
[0057] In addition to the above-described flaky metal pigment, the
metallic composition according to the second embodiment can include
optional elements, for example, a resin, a solvent, a color pigment
(for example, an inorganic pigment, an organic pigment, and the
like), and the like. Furthermore, it may also include: dispersants
such as a surfactant: or stabilizing agents such as an antioxidant
and an ultraviolet absorber.
[0058] As the above-described resin, a combination of two or more
of the following elements is suitably used, which include an epoxy
resin, a polyester resin, an acrylic resin, an acrylic silicone
resin, a vinyl resin, a silicon resin, a polyamide resin, a
polyamideimide resin, a fluorine resin, boiled oil, chlorinated
rubber, an amino resin, a phenol resin, a polyisocyanate resin, a
urea resin, and the like.
[0059] Examples of the above-described solvent can be an
alcohol-based, a glycol-based, a ketone-based, an ester-based, an
ether-based, an aromatic-based, or a hydrocarbon-based organic
solvent, water, and the like. In the case where water is used and
also the case where the above-described flaky metal pigment
contains aluminum or is made of aluminum, it is preferable that the
surface of the flaky metal pigment is coated with an optional
coating film in order to suppress the reaction between water and
aluminum. Such a coating film can be a coating film, for example,
made of metal oxide, resin, and the like.
[0060] In the metallic composition according to the second
embodiment, the amount of flaky metal pigments blended in the
metallic composition is not particularly limited. The blending
amount varies depending on applications, and generally, preferably
falls within a range of 0.1 mass % or more and 80 mass % or less.
Particularly, in order to suitably use the metallic composition
according to the second embodiment as a metallic composition for
ink jetting, the blending amount is preferably 0.1 mass % or more
and 30 mass % or less, more preferably 0.5 mass % or more and 20
mass % or less, and further more preferably 0.5 mass % or more and
10 mass % or less. In the case where the amount of flaky metal
pigments blended in the metallic composition for ink jetting
exceeds 30 mass %, the metallic composition cannot be kept in a
slurry state but turns into a paste state, and therefore, tends to
be difficult to be discharged through the ink-jet nozzle.
Furthermore, in the case where the blending amount is less than 0.5
mass %, formation of an image having a sufficient concentration
tends to be difficult.
[0061] In addition, as an ink-jet discharging method using the
metallic composition according to the second embodiment, various
methods can be employed, which can for example be a drop-on-demand
method (or a pressure pulse method) by which ink (a metallic
composition) is discharged utilizing electrostatic attraction
force; a bubble method (or a thermal jet method) by which ink (a
metallic composition) is discharged utilizing pressure produced by
growth of air bubbles formed by high temperature; and the like.
[0062] Furthermore, in the case where the metallic composition
according to the second embodiment is coated on a base body, the
material of the base body to be coated is not particularly limited,
and can be inorganic substances such as metal, ceramics and glass,
a synthetic resin, paper, various types of electronic substrates,
and the like. Particularly in the case where the metallic
composition according to the second embodiment is used for ink
jetting, examples of the base body can be papers including
non-coated printing paper, coated printing paper such as coated
paper and glossy paper; substrates made of a synthetic resin film,
a synthetic resin molded body, glass, metal, wiring, and the like;
and fibers such as clothing.
[0063] The metallic composition having been specifically described
above can be manufactured by a known manufacturing method. For
example, after the flaky metal pigments according to the first
embodiment, a dispersant, and a solvent are mixed, the obtained
dispersion liquid is prepared using a stirrer, a ball mill, a bead
mill, an ultrasonic wave, a jet mill, or the like. Then, a
surfactant, resin, and other additives are added to the prepared
dispersion liquid while being stirred, so that a metallic
composition can be manufactured.
Third Embodiment: Coated Product
[0064] The coated product according to the third embodiment is
obtained by applying a metallic composition according to the second
embodiment. It is to be noted that the coated product means a
product obtained by applying a metallic composition onto an object
to be coated by means of coating or the like.
[0065] In the coated product according to the third embodiment, the
flaky metal pigment that tends to be smaller in particle size than
the conventional pigment is applied. Accordingly, the coated
product exhibits an excellent metallic texture, and also, the
object to be coated is sufficiently shielded by the flaky metal
pigments.
[0066] The thickness of the coating film applied on the coated
product according to the third embodiment is not particularly
limited, but another underlying layer may be provided under this
coating film, and another coat layer may also be provided on this
coating film. In addition, since an explanation of the object to be
coated according to the third embodiment is the same as that of the
base body described in the second embodiment, the description
thereof will not be repeated.
Fourth Embodiment: Method of Manufacturing Flaky Metal Pigment
[0067] The method of manufacturing a flaky metal pigment according
to the fourth embodiment is a method of manufacturing a flaky metal
pigment, and particularly suitable for manufacturing the flaky
metal pigment according to the first embodiment. Specifically,
referring to FIG. 1, the method includes the steps of: preparing
slurry including a flake made of metal (a slurry preparing step:
step S11); and fine-graining the flake by jetting the slurry at
high pressure (fine-graining step: step S12). Referring to FIGS. 1
to 6, an example of the method of manufacturing a flaky metal
pigment made of aluminum will be hereinafter described in
detail.
[0068] <Slurry Preparing Step>
[0069] Referring to FIG. 1, in the manufacturing method according
to the fourth embodiment, slurry including flakes each made of
aluminum is first prepared (step S11). The prepared slurry includes
aluminum flakes made of aluminum and a solvent.
[0070] FIG. 2(a) shows a schematic side view illustrating an
example of the shape of a flake made of aluminum (which will be
hereinafter referred to as an "Al flake"). FIG. 2(b) shows a
schematic plan view illustrating an example of the shape of the Al
flake. Referring to FIG. 2(a), Al flake 10 has a thickness t.sub.0
that is preferably 5 nm or more and 25 nm or less, and more
preferably 10 nm or more and 25 nm or less.
[0071] In this case, average thickness t of the flaky metal
pigments to be manufactured is readily adjusted to be 5 nm or more
and 25 nm or less. Furthermore, in the fine-graining step described
later, Al flake 10 can be fine-grained efficiently. Furthermore, in
the case where average thickness t exceeds 25 nm, the mechanical
strength of the prepared Al flake 10 is increased, thereby
lengthening the time of the fine-graining step, so that the
productivity tends to significantly deteriorate.
[0072] Furthermore, particle size D50 of Al flake 10 is not
particularly limited, but is preferably 1 .mu.m or more and 50
.mu.m or less. In the case where particle size D50 of Al flake 10
is 50 .mu.m or less, in the fine-graining step described later,
clogging of the nozzle for fine-graining can be suppressed while
fine-graining can be achieved efficiently in a short period of
time. Furthermore, it is substantially difficult to industrially
obtain Al flake 10 having particle size D50 of less than 1 .mu.m.
It is to be noted that particle size D50 means a particle size
having a cumulative degree of 50% in the volume cumulative particle
size distribution measured by laser diffractometry.
[0073] Al flake 10 as described above can be manufactured by the
ball mill method, the vacuum vapor deposition method, and the like.
In the fourth embodiment, it is preferable that a flake
manufactured by the vacuum vapor deposition method is used as Al
flake 10. This is because Al flake 10 manufactured by the vacuum
vapor deposition method can have smooth and flat surfaces 10a and
10b while having thickness t.sub.0 that is relatively more uniform
and thinner than that obtained by the ball mill method.
[0074] An example of the vacuum vapor deposition method will be
hereinafter described. First, a sheet-like base member, or a
sheet-like base member having a surface on which a peeling resin
layer is formed is prepared. The sheet-like base member to be used
can for example be a film made of PET (polyethylene terephthalate)
and the like. As a peeling resin layer, a coating film made of
polyvinyl alcohol or the like can be used.
[0075] Then, a vapor deposition layer made of aluminum is formed by
the vacuum vapor deposition method on the surface of the sheet-like
base member (or if a peeling resin layer is formed, on the surface
of this peeling resin layer). In the case where a peeling resin
layer is used, peeling resin layers and vapor deposition layers are
alternately stacked multiple times to provide a multi-layer
structure. This vapor deposition layer is formed to have a
thickness of 5 nm or more and 25 nm or less, so that thickness
t.sub.0 of Al flake 10 can be readily adjusted to be 5 nm or more
and 25 nm or less. In addition, it is substantially difficult to
form an aluminum layer having a thickness of less than 5 nm as a
uniform continuous layer on the sheet-like base member or on the
peeling resin layer on the surface of the sheet-like base
member.
[0076] Then, an aluminum vapor deposition layer is peeled at the
surface of the sheet-like base member (or if a peeling resin layer
is formed, at the surface of the peeling resin layer) defined as a
boundary. This peeled aluminum vapor deposition layer is pulverized
to obtain Al flakes 10. In addition, the peeled aluminum vapor
deposition layer is subjected to an ultrasonic treatment as
required, so that particle size D50 of Al flake 10 may be reduced
to some extent. Thereby, the time required for the fine-graining
step described later can be shortened.
[0077] The method of peeling an aluminum vapor deposition layer
includes a method of peeling an aluminum vapor deposition layer for
example by immersing a sheet-like base member, which has an
aluminum vapor deposition layer formed thereon, in a solvent in
which the sheet-like base member or the peeling resin layer is to
be dissolved. In general, a method of dissolving the peeling resin
layer to peel the aluminum vapor deposition layer from the
sheet-like base member is employed. In this case, the peeled
aluminum vapor deposition layer is present in a solvent.
Accordingly, for example, by subjecting this solvent to an
ultrasonic treatment, the peeled aluminum vapor deposition layer
can be pulverized.
[0078] Furthermore, another method of peeling the aluminum vapor
deposition layer includes, for example, a method of physically
peeling the aluminum vapor deposition layer from the sheet-like
base member or the peeling resin layer. In this case, the peeled
aluminum vapor deposition layer is crushed by a crusher or the
like, so that this peeled aluminum vapor deposition layer can be
pulverized.
[0079] Furthermore, a commercially available PVD pigment may be
used as Al flake 10. The PVD pigment generally means a flake made
of metal manufactured using the vacuum vapor deposition method as
described above.
[0080] In addition, even if pulverization is carried out for an
excessively long period of time by a ultrasonic treatment or the
like without considering the industrial productivity, it is
difficult to set P50 to be less than 0.500 .mu.m for the particle
size as in the case of the flaky metal pigment of the present
invention, and its particle size distribution becomes extremely
broad.
[0081] A solvent included in the slurry can be any of water, a
hydrophilic organic solvent and a hydrophobic organic solvent.
Since water is more likely to react with aluminum, it is preferable
to use an organic solvent when the flaky metal pigment is made of
aluminum. Examples of the hydrophilic organic solvent includes
glycol-based solvents such as ethylene glycol, methyl ethyl
diglycol, ethylene glycol monobutyl ether (butyl cellosolve),
diethylene glycol monobutyl ether, triethylene glycol monoethyl
ether, propylene glycol monomethyl ether, propylene glycol
monoethyl ether, propylene glycol monopropyl ether, dipropylene
glycol monomethyl ether, dipropylene glycol monoethyl ether; glycol
acetate-based solvents such as propylene glycol monomethyl ether
acetate and ethyl diglycol acetate; alcohol-based solvents such as
isopropyl alcohol; and the like. Examples of the hydrophobic
organic solvent include aliphatic hydrocarbons such as mineral
spirit, isoparaffin, normal paraffin, and petroleum benzene; and
aromatic hydrocarbons such as xylene, toluene, and solvent
naphtha.
[0082] The solid content (that is, the content ratio of Al flakes
10) in the slurry is not particularly limited, but only has to be
able to be jetted in the fine-graining step described later. For
example, the content of Al flakes 10 to the total weight of the
slurry is preferably 1 mass % or more and 30 mass % or less, more
preferably 1 mass % or more and 20 mass % or less, and further more
preferably 1 mass % or more and 10 mass % or less. When the content
exceeds 30 mass %, the slurry cannot be kept in its state and turns
into paste, which tends to be difficult to be jetted from the
nozzle for fine-graining. Furthermore, in the case where the
content is less than 1 mass %, the efficiency of the fine-graining
step may decrease.
[0083] In the case where the obtained Al flakes 10 are present in
the solvent, if the mixture of Al flakes 10 and the solvent is in
the slurry state, this mixture can be used as it is in the
fine-graining step described later. Furthermore, in the case where
the solid content in the mixture is relatively high and the mixture
is in a paste state, a solvent is further added to this mixture to
adjust the solid content in the mixture to fall within an
appropriate range (viscosity), so that the obtained mixture can be
used in the fine-graining step described later. In this case, it is
preferable that a solvent described later is used as a solvent used
for peeling the aluminum vapor deposition layer. In addition, a
commercially available Al flake is often in a slurry state.
[0084] On the other hand, in the case where the obtained Al flakes
10 are present as powder, a solvent is added to Al flakes 10 to
adjust the solid content in the mixture to fall within an
appropriate range, so that the obtained mixture can be used in the
fine-graining step described later.
[0085] <Fine-Graining Step>
[0086] Referring to FIG. 1, after the above-described slurry
preparing step, the prepared slurry is jetted at high pressure to
fine-grain Al flake 10 (step S12). Thereby, surface 10a and surface
10b of Al flake 10 are separated and fine-grained. Consequently, it
becomes possible to manufacture a flaky metal pigment in which P50
showing a 50% cumulative frequency of the diameter equivalent to an
area circle in the number distribution is less than 0.500
.mu.m.
[0087] The method of fine-graining an Al flake by jetting at high
pressure is to apply pressure to slurry to be jetted at high speed
and apply physical force to Al flake 10 included in the jetted
slurry so as to be crushed. When comparing the flaky metal pigment
that is fine-grained in the present step and the Al flake prepared
in the slurry preparing step, the thicknesses of the pigment and
the flake are relatively similar to each other, whereas the
particle sizes thereof are to be greatly different from each other.
A method of fine-graining a Al flake by jetting slurry at high
pressure can be methods (1) to (4) as described below.
[0088] (1) The slurry accelerated by pressurization is caused to
collide with a hard body to cause the Al flake included in the
slurry to collide with the hard body, thereby fine-graining the Al
flake.
[0089] (2) As disclosed in U.S. Pat. No. 3,151,706 (Japanese Patent
Laying-Open No. 10-337457), the slurries accelerated by
pressurization are caused to collide with each other to cause the
Al flakes included in the slurries to collide with each other,
thereby fine-graining each Al flake.
[0090] (3) By using a combination of the above-described methods
(1) and (2), the accelerated slurries are caused to collide with
each other and also to collide with a hard body, thereby
fine-graining each Al flake.
[0091] (4) Slurry is accelerated by pressurization to cause
cavitation to occur in the slurry (a phenomenon in which a low
pressure portion in the raw material flowing at high speed in the
pressurized state is vaporized to produce pockets of vapor in an
extremely short period of time, and the produced pockets of vapor
collapse and disappear in an extremely short period of time), and
then, each Al flake is fine-grained by the impact caused by
production and disappearance of air bubbles within the slurry.
[0092] In the fourth embodiment, it is preferable to use the
above-described method (1) or (2) since it allows highly efficient
fine-graining and also allows production of a flaky metal pigment
having a desired particle size in a short period of time.
Particularly, the above-described method (1) is further preferable
since it is more efficient in fine-graining than the
above-described method (2). The above-described method (1) will be
hereinafter specifically described with reference to FIGS. 3 and 4,
and the above-described method (2) will be hereinafter specifically
described with reference to FIGS. 5 and 6.
[0093] The above-described method (1) will be first described.
[0094] Referring to FIGS. 3 and 4, first, in step S31, slurry is
jetted from a nozzle 41 as a jetting unit into a reaction chamber
40 at a pressure of 70 MPa or more (jetting step). It is to be
noted that the arrow in the figure shows a direction in which the
slurry is jetted. Then, in step S32, Al flakes 10 included in the
jetted slurry are caused to collide with a hard body 42 disposed
within reaction chamber 40 (collision step). Thereby, each Al flake
10 is fine-grained. The slurry having been fine-grained is removed
through a discharge unit 43 to the outside of reaction chamber
40.
[0095] The pressure applied to the slurry while being jetting from
nozzle 41 is preferably 70 MPa or more and 250 MPa or less, and
more preferably 100 MPa or more and 250 MPa or less. The present
inventor confirmed that Al flake 10 can be fine-grained efficiently
under such pressure conditions.
[0096] Furthermore, although the diameter of the discharge port of
nozzle 41 is not particularly limited, it is preferably 0.1 mm or
more and 0.5 mm or less, more preferably 0.1 mm or more and 0.30 mm
or less, and further more preferably 0.1 mm or more and 0.15 mm or
less. In this case, slurry can be jetted at high speed and clogging
of nozzle 41 can also be sufficiently suppressed.
[0097] The quality of the material of hard body 42 is not
particularly limited, but only has to be higher in hardness than Al
flake 10. Examples of such material can be ceramics such as
SiN.
[0098] Furthermore, the flow rate of slurry is preferably 10 L/hour
or more and 200 L/hour or less, and more preferably 40 L/hour or
more and 150 L/hour or less. The present inventor confirmed that Al
flake 10 can be fine-grained efficiently at such a flow rate.
[0099] Furthermore, the slurry jetted into reaction chamber 40 can
be caused to flow from a reflux port (not shown) back into nozzle
41 and jetted again. Accordingly, when the present step is
performed using a prescribed amount of slurry, the jetting time is
set so as to be relatively long to cause the slurry to reflux, so
that the slurry can be repeatedly caused to collide with hard body
42. The total amount of the slurry provided in the present step is
not particularly limited. In the case where the total amount is 50
g or more and 500 g or less, this jetting time (processing time) is
preferably 0.05 hours or more and 50 hours or less, and more
preferably 1 hour or more and 20 hours or less. In this case, the
balance between fine-graining and the processing time is
excellent.
[0100] Furthermore, in the present step, the temperature of the
slurry is preferably 5.degree. C. or more and 250.degree. C. or
less, and more preferably 5.degree. C. or more and 150.degree. C.
or less, the reason of which will be described below. Specifically,
the temperature of slurry tends to rise by jetting the slurry at
high pressure. It is feared that the temperature of the slurry may
reach the boiling point of the solvent, the spontaneous ignition
temperature or the like if it excessively rises. In contrast, this
temperature is controlled to be set at at least 250.degree. C. or
less, thereby allowing a wide range of selections of solvents to be
made, so that evaporation, ignition and the like of the solvent can
be suppressed. Furthermore, since the solvent can exist stably
during the present step, the stability of the fine-graining process
is improved.
[0101] The above-described method (2) will be hereinafter
described.
[0102] Referring to FIGS. 5 and 6, first, in step S51, the slurry
is jetted from two nozzles 61a and 61b as jetting units into a
reaction chamber 60 under a pressure of 70 MPa or more (jetting
step). Although the number of nozzles is two in FIG. 6, the
above-described method (2) is not limited thereto. The arrows in
the figure show directions in which each slurry is jetted. Then, in
step S52, the slurry jetted from nozzle 61a and the slurry jetted
from 61b are caused to collide with each other, thereby causing the
Al flakes included in these slurries to collide with each other
(collision step). Thereby, each Al flake 10 is fine-grained. The
slurry having been fine-grained is removed through discharge unit
62 to the outside of reaction chamber 60.
[0103] In the above-described method (2), the preferable ranges for
other conditions such as pressure are the same as those in the
above-described method (1), and therefore, the description thereof
will not be repeated.
[0104] Although the above-described methods (1) and (2) have been
specifically described, examples of an apparatus capable of
performing the fine-graining step by means of high-pressure jetting
as described above can be "Genus PY" manufactured by Genus, Inc.,
"Star Burst" manufactured by Sugino Machine Limited, "Nanomizer"
manufactured by NANOMIZER Inc., and the like. Particularly, by
selecting various configurations of reaction chambers used in the
jetting step, "Star Burst" can be suitably utilized in the
above-described methods (1), (2), and (4); "Genus PY" can be
suitably utilized in the above-described method (3); and
"Nanomizer" can be suitably utilized in the above-described method
(4).
[0105] In the method of manufacturing a flaky metal pigment
according to the fourth embodiment as specifically described above,
the slurry preparing step and the fine-graining step are performed,
thereby allowing production of a flaky metal pigment in which P50
showing a 50% cumulative frequency of the diameter equivalent to an
area circle in the number distribution is less than 0.500 .mu.m.
The flaky metal pigment having such a particle size could not be
manufactured by the conventional manufacturing method.
[0106] Furthermore, Pmax for the flaky metal pigment manufactured
by the method of manufacturing a flaky metal pigment according to
the fourth embodiment can also be set at 5.000 .mu.m or less.
Furthermore, Pmax/P10 for the flaky metal pigment (in which case
the unit of Pmax and the unit of P10 are the same) can be set at 1
or more and 18 or less. Consequently, the obtained flaky metal
pigments tend to be sharper in particle size distribution than
those manufactured by the conventional manufacturing method.
Accordingly, such flaky metal pigments can be suitably used for
metallic printing by ink jetting, which requires high
definition.
EXAMPLES
[0107] Although the present invention will be hereinafter described
in greater detail with reference to Examples, the present invention
is not limited thereto.
Example 1
[0108] As a flaky metal pigment, a flaky aluminum pigment according
to Example 1 was produced as described below.
[0109] First, a commercially available PVD pigment was prepared.
The characteristics of this PVD pigment were as described
below.
[0110] Thickness of Al flake: 0.02 .mu.m
[0111] Particle size of Al flake (D50): 9 .mu.m
[0112] Solid content in slurry: 10 mass %
[0113] Solvent included in slurry: Propylene glycol monomethyl
ether acetate (which will be hereinafter abbreviated as "PMA").
[0114] By two-fold dilution of the above-described PVD pigments
with PMA, 2000 g of slurry made of PMA and Al flakes and having a
solid content of 5 mass % was prepared (slurry preparing step).
[0115] Then, the trade name "Star Burst Labo" manufactured by
Sugino Machine Limited was used to jet the prepared slurry at high
pressure, so that each Al flake is fine-grained by the
above-described method (1) (a method of causing the slurry
accelerated by pressurization to collide with a hard body to
thereby cause the Al flakes included in the slurry to collide with
the hard body, so that each Al flake is fine-grained)
(fine-graining step). The conditions in the fine-graining step were
as described below.
[0116] Pressure applied to slurry: 200 MPa
[0117] Diameter of discharge port of nozzle: 0.2 mm
[0118] Material of hard body: SiN
[0119] Flow rate of slurry: 60 L/hour
[0120] Jetting time: 4 hours
[0121] Motor capacitance: 7.5 kW.
[0122] After the above-described fine-graining step, a slurried
sample A including the fine-grained flaky metal pigments according
to the present invention was removed from the "Star Burst Labo".
The removed sample A, which was slurry made of PMA and flaky
aluminum pigments, had a solid content of 5 mass %.
Comparative Example 1
[0123] After preparing the slurry by the same method as that in
Example 1, an ultrasonic homogenizer (trade name: "MODEL US-300T"
manufactured by NIHONSEIKI KAISHA LTD.) was used to perform an
ultrasonic treatment in place of the above-described fine-graining
step. The amount of slurry used in the treatment was 350 g, which
was preparatively separated in a 500-ml PP cup. In addition, since
the ultrasonic pulverization causes heat generation, the slurry was
pulverized while being continuously immersed in a bath containing
ice water. The conditions of the ultrasonic treatment were as
described below.
[0124] Used chip: standard chip (26.phi.)
[0125] V-LEVEL: 400 .mu.A
[0126] Treatment time: 5 hours.
[0127] A sample B obtained after the above-described ultrasonic
treatment was slurry made of PMA and flaky aluminum pigments, and
had a solid content of 5 mass %.
[0128] <Analysis by Flow-Type Particle Image Analyzer>
[0129] Sample A obtained in Example 1 and sample B obtained in
Comparative Example 1 each were subjected to a flow-type particle
image analyzer, to measure P50, Pmax, and P10. In addition,
"FPIA-3000S" manufactured by Sysmex Corporation was used as a
flow-type particle image analyzer under the measurement conditions
as described above.
[0130] <Average Thickness of Flaky Metal Pigments>
[0131] Average thickness t of flaky metal pigments (flaky aluminum
pigments) included in each of sample A and sample B was calculated
according to the above-described method using an atomic force
microscope (trade name: "Nanopics 1000" manufactured by Seiko
Instruments Inc).
TABLE-US-00001 TABLE 1 P50 Pmax P10 t (.mu.m) (.mu.m) (.mu.m)
(.mu.m) P50/t Pmax/P10 Example 1 0.474 3.359 0.307 0.0187 25.3 10.9
Comparative 1.012 9.629 0.494 0.0187 54.1 19.5 Example 1
[0132] Measurement results and calculation results about each of
samples A and B are shown in Table 1. As shown in Table 1, sample A
obtained in Example 1 had P50 of 0.474 .mu.m, Pmax of 3.359 .mu.m,
P10 of 0.307 .mu.m, and average thickness t of 0.0187 .mu.m. Also,
sample B obtained in Comparative Example 1 had P50 of 1.012 .mu.m,
Pmax of 9.629 .mu.m, P10 of 0.494 .mu.m, and average thickness t of
0.0187 .mu.m. Furthermore, Table 1 shows values of P50/t and
Pmax/P10 based on the obtained results.
[0133] Referring to Table 1, it was confirmed that the flaky
aluminum pigment included in sample A obtained in Example 1 had P50
of less than 0.5 .mu.m. Furthermore, it was confirmed that sample A
in Example 1 had Pmax of 5.000 .mu.m or less. Furthermore, it was
found that sample A in Example 1 was smaller in value of Pmax/P10
and sharper in particle size distribution than sample B in
Comparative Example 1.
[0134] <Characteristic Evaluation of Coating Film>
[0135] Samples A and B were used to produce a metallic composition
A for evaluation and a metallic composition B for evaluation, which
were then used to produce a coating film's characteristic
evaluation film A and a coating film's characteristic evaluation
film B by the method described below. Then, the characteristics of
both coating films were evaluated by the method described
below.
[0136] (Production of Characteristic Evaluation Film)
[0137] The metallic composition for evaluation and the coating
film's characteristic evaluation film were produced as described
below. First, after sample A obtained in the above-described
Example 1 was weighed so as to set the amount of solid content of
the flaky aluminum pigments at 1.0 parts by mass, sample A was
diluted with 10 parts by mass of ethyl acetate, to which 4 parts by
mass of pyroxylin lacquer (a mixture including 14 wt % of
pyroxylin, with the rest made up of solvents such as toluene, ethyl
acetate and alcohol, and additive components) was added, thereby
preparing metallic composition A for evaluation. Similarly, sample
B obtained in Comparative Example 1 was used to prepare metallic
composition B for evaluation.
[0138] Then, an automatic coating apparatus (trade name: "PI-1210"
manufactured by Tester Sangyo CO., LTD.) was used to apply metallic
composition A for evaluation prepared as described above onto a PET
film (using a bar coater #8, wet thickness: about 18.3 .mu.m, speed
7), which was then naturally dried at a room temperature
(25.degree. C.) in the air for 1 hour. Consequently, coating film's
characteristic evaluation film A was produced. Similarly, metallic
composition B for evaluation prepared as described above was used
to produce an evaluation film B. The obtained evaluation films A
and B each had a metallic texture. In addition, since each flaky
aluminum pigment included in the slurry in Comparative Example 1
had a relatively large particle size and therefore was difficult to
be applied to an ink jet printer, each coating film was produced by
an automatic coating apparatus in this case.
[0139] (Shielding Performance Evaluation 1)
[0140] The visible light transmittance of each of the produced
evaluation films A and B was measured. The visible light
transmittance was measured using a transmittance measurement
apparatus (trade name: "Z-1001DP" manufactured by NIPPON DENSHOKU
INDUSTRIES CO., LTD.). The smaller the value of the visible light
transmittance is, the less the light is likely to be transmitted,
which means that the shielding ability is relatively high. In
addition, the transmittances were respectively calculated based on
the transmittance of the PET film before forming a coating film
defined as 100%, which were then compared for measurement.
[0141] (Shielding Performance Evaluation 2)
[0142] The shielding abilities of the produced evaluation films A
and B were visually observed. Specifically, an upright-standing
type artificial sunlight lamp (manufactured by SERIC., Ltd., main
body XC-100 type, stand type, ST-1500C) was used to visually
evaluate the light transmittance (shielding ability) of the coating
film at 10 stages. In this case, 0 shows an uncoated PET film and
10 shows the state where light is completely shielded.
TABLE-US-00002 TABLE 2 Shielding Performance Shielding Performance
Evaluation 1 Evaluation 2 Transmittance (%) Shielding Ability
Example 1 6.8 5 Comparative 7.2 4 Example 1
[0143] The results of shielding performance evaluations 1 and 2 are
shown in Table 2. As shown in Table 2, shielding performance
evaluation 1 showed that evaluation film A was lower in
transmittance than evaluation film B. Furthermore, shielding
performance evaluation 2 showed that evaluation film A was higher
in shielding ability than evaluation film B. Accordingly, it turned
out that the flaky aluminum pigment in Example 1 can exhibit
relatively high shielding performance.
[0144] Although the embodiments and examples according to the
present invention have been described as above, the configurations
of the embodiments and examples described above are intended to be
combined as appropriate from the beginning.
[0145] It should be understood that the embodiments and examples
disclosed herein are illustrative and non-restrictive in every
respect. The scope of the present invention is defined by the terms
of the claims, rather than the description above, and is intended
to include any modifications within the meaning and scope
equivalent to the terms of the claims.
* * * * *